== Backward incompatible changes in XIOS 2.0 ==

Although we try to limit them as much as possible, there are some backward incompatible changes that you may notice when migrating from XIOS 1.0 to XIOS 2.O.

This document lists all those changes at the time it was written and might not always be up-to-date due to XIOS 2.0 still being in development.

- the `type` attribute of the `variable` object is now more strictly checked. It must be one of:
  - `bool`
  - `int` or `int32`
  - `int16`
  - `int64`
  - `float`
  - `double`
  - `string`.

  For example, `<variable id="my_attribute2" type="integer" >10</variable>` will become `<variable id="my_attribute2" type="int" >10</variable>` and `<variable id="print_file" type="boolean">true</variable>` will become `<variable id="print_file" type="bool">true</variable>`.
- attributes corresponding to a duration should now be manipulated using the `xios_duration` type when using the Fortran interface. Affected attributes are:
  - `timestep` in `context` objects
  - `freq_op` and `freq_offset` in `field` objects
  - `output_freq`, `sync_freq` and `split_freq` in `file` objects.

  Note that the old `xios_time` type have been removed.

  The following code:
  {{{
  PROGRAM test
    USE xios
    ...
    TYPE(xios_time) :: dtime
    ...
    CALL xios_get_handle("test",ctx_hdl)
    CALL xios_set_current_context(ctx_hdl)
    ...
    dtime%second=3600
    CALL xios_set_timestep(dtime)
    ...
  END PROGRAM test
  }}}
  will become:
  {{{
  PROGRAM test
    USE xios
    ...
    TYPE(xios_duration) :: dtime
    ...
    CALL xios_get_handle("test",ctx_hdl)
    CALL xios_set_current_context(ctx_hdl)
    ...
    dtime%second=3600
    CALL xios_set_timestep(dtime)
    ...
  END PROGRAM test
  }}}
  or
  {{{
  PROGRAM test
    USE xios
    ...
    TYPE(xios_duration) :: dtime
    ...
    CALL xios_get_handle("test",ctx_hdl)
    CALL xios_set_current_context(ctx_hdl)
    ...
    dtime%second=3600
    CALL xios_set_context_attr("test", timestep=dtime)
    ...
  END PROGRAM test
  }}}
- attributes corresponding to a date should now be manipulated using the `xios_date` type when using the Fortran interface. Affected attributes are `start_date` and `time_origin` in `context` objects.

  The following code:
  {{{
  PROGRAM test
    USE xios
    ...
    CALL xios_set_context_attr("test",calendar_type="Gregorian")
    CALL xios_set_context_attr("test",start_date="2000-01-01 00:00:00")
    CALL xios_set_context_attr("test",time_origin="1999-01-01 15:00:00")
    ...
  END PROGRAM test
  }}}
  will become:
  {{{
  PROGRAM test
    USE xios
    ...
    TYPE(xios_date) :: start_date, time_origin
    ...
    CALL xios_set_context_attr("test",calendar_type="Gregorian") 
    start_date = xios_date(2000, 01, 01, 00, 00, 00) 
    CALL xios_set_context_attr("test",start_date=start_date) 
    time_origin = xios_date(1999, 01, 01, 15, 00, 00) 
    CALL xios_set_context_attr("test",time_origin=time_origin) 
    ...
  END PROGRAM test
  }}}